NOVA teams up with National Geographic to explore why mysterious rat plagues ravage northeast India every 48 years.

The program:

travels to the northeastern Indian state of Mizoram, where rats are estimated to have eaten more than 50,000 metric tons of rice, devastating the farmers' fields.

visits the remote village of Thlangkang, where rats have devoured farmers' rice and corn crops.

reports that the majority of rats causing the damage are black rats, likely because their rapid breeding and early weaning give them an advantage over their competitors.

reveals that the rat population explodes every 48 years, coinciding with the blossoming and fruiting of the local bamboo plant, an ecological event known by the local people as mautam.

follows biologists to the Mizoram village of Zamuang, where the mautam has occurred but the rats have not yet invaded the fields.

notes that although black rats are normally kept in check because the forest offers little to eat, over the course of the bamboo fruiting each of the well-fed females can start a cycle that results in up to 200 offspring.

states that bamboo is a grass that is inexpensive, versatile in its use, and ten times stronger than steel.

describes how bamboo spreads by underground rhizomes.

explains that the large fruiting event ensures the plant's survival—so much seed is produced that predators cannot eat it all, thus allowing the plant to germinate and produce new bamboo.

introduces four methods biologists use to determine how many rats are in one farmer's rice field and the forest that surrounds it.